Hoboken Begins 'Twenty is Plenty' Driving Speed Campaign

Ian Sacs's picture

This week, Hoboken is announcing its version of a highly successful awareness campaign practiced throughout Europe and, more directly translatable, the UK. In the UK, the campaign is called "20's Plenty for Us", and in cities that adopt this policy, a 20mph speed limit area is established and signs are posted requiring drivers to obey the lower speed limit. While such a policy sends a strong message that residential and downtown areas should be synonymous to slow driving, illustrated in this production by streetfilms, implementation stateside is not nearly so easy. In Hoboken's version, "Twenty is Plenty", we are campaigning that drivers "consider driving" 5mph slower than the posted 25mph speed limit because this small change in speed has a major impact on the chances of fatality in a pedestrian-vehicle collision. We'd love to enact a lower city-wide speed limit, but we are bound to traffic engineering guidelines that were established when driving a car fast was all that mattered. If drivers agree with the message and choose to slow down, changing the speed limit may eventually come within reach.  Will an appeal to sensibilities and safety work as well as a regulatory change?

Hoboken's "Twenty is Plenty" Flyer Makes An Appeal, Not A Rule

Thanks to us (we?) awesome traffic engineers, changing speed limits is not as simple as merely adopting such policy. You can't look at fast cars on a road that has a speed limit of 45mph and just decide that the speed limit should be changed to 35mph. The reason for this is twofold: First, most roads are engineered with a "design speed" that is generally 10mph higher than the anticipated speed limit. In the era of go-fast-twentieth-century-highway-skewed traffic engineering, assuming a faster design speed above an already high speed limit (where "limit" means the fastest one should be legally driving) is unfortunately how things were done. Perhaps this makes sense on highways, but the same rules have traditionally been applied to city streets. To the driver this translates to a road that "feels" safe when driving at or slightly above the posted speed limit, so merely changing the posted speed limit will not change the so-called "perceived risk" of the driver who will continue to drive at the speed that, to him, feels safe. Enforcement addresses this somewhat, but that's an uphill battle.

The second - and more restrictive - reason you can't just come along and change a speed limit is because there are specific traffic engineering guidelines on how a speed limit is changed, and they have absolutely nothing to do with the safety of bicycle riders or pedestrians on that street; instead, they are skewed towards accommodating an assumption that speed limits may sometimes need to be raised. More specifically, if an engineering speed study shows that an appreciable number of drivers regularly exceed the speed limit, a traffic engineer is justified in recommending that the speed limit be lifted. Sure, you can certainly use this same guidance to demonstrate that cars are driving slower, and therefore the speed limit should be lowered, but come on, who are we fooling?

It's certainly a conundrum. So how then do you get vehicles to drive at slower speeds when the gods of traffic engineering have sent you on an upward spiral? We think the answer may be outreach modeled on the UK campaign that does all but establish a new speed limit, at least in the short term. The idea is that if we appeal to the safety aspects of driving slower, and make the case that neighbors and relatives are the people using the same streets we drive on, then perhaps slower driving will become the norm and those pesky engineering studies can be used to eventually seal the deal. It's sneaky, but it could possibly work. What do you think?

Note: New York City recently announced a similar pilot study where they are "testing the feasibility" of lowering speed limits to 20mph on some residential streets. It will be interesting to see how the two parallel efforts, slightly different but with the same objective, pan out.

Ian Sacs, P.E. is a worldwide transportation solutions consultant based in Finland.



Speed Limits

Maybe it is time to make speed limits, and other road issues, a planning and political decision, instead of an engineering decision?

Ken Firestone

Ian Sacs's picture

Ian Sacs Replies

That works when the safety element is taken out of it, or assuming all politicians and planners are working with safety as the priority. Unfortunately, leave speed limits up to many politicians, and their hired planners, and we'd have autobahns along urban arterials. In fact, this kind of frustration often happens in projects. Architects and planners have a great time putting together a project that looks great, and then engineers come and muck it all up late in the design process.

I'm reminded of early years when a developer, and his architect, would get bent out of shape when we'd inform them that their driveways were too short, or should be transposed to avoid vehicle turning conflicts, etc. Taking the engineers out of the equation is not exactly the best way to handle the situation, bringing them in form the outset is more likely to result in an enjoyable outcome.

For speed limits, I submit that taking engineers out of the equation is also not the way forward. At this year's Institute for Transportation Engineers conference I was shocked by how intense the pace was by my colleagues at designing complete streets and addressing design challenges that have come up; there was excitement about "solving" a new problem. Engineers are fantastic at solving problems, and I believe politicians and planners need them to assist in that effort. It's simply the ground rules that need to be set by others.

Speed Limits and Way of Life

I agree with Ken Firestone that speed limits should be seen as a political choice, because they involve choosing one's way of life. This is the point I made in my opinion piece at http://www.planetizen.com/node/44299

That doesn't mean we should leave the decision to politicians who want to pander to the public's current perceptions. It means public perceptions need to shift: today, the public generally thinks of road design as an engineering problem and doesn't see that it affects how you live.

It also doesn't mean that we should take engineers out of the equation. After the public makes its political choice, we need engineers to design the roads that suit that choice. And, in fact, the engineers can provide valuable information that helps the public make the right choices.

The change in the way we look at urban freeways is a good example of the change we need more generally.

In the 1950s, the decision about whether an urban freeway should be built was considered a technical question that the engineers should decide on the basis of projected traffic volumes.

In the 1960s and 1970s, people started talking about how urban freeways affect the "quality of life." By seeing it as a decision about how we live rather than a purely technical decision, they made it possible to start a political movement to stop urban freeways.

Today, some cities are tearing down freeways to improve the quality of life. Engineers are needed to calculate the policies that will make the freeway removal possible: what policies are needed to reduce VMT and how much street capacity is needed to replace the freeway. Engineers are also needed to design the boulevards or the street grids that replace the demolished freeways. But the decision to remove the freeway is fundamentally a political decision, not a technical decision: we are able to remove freeways because we realize that it is a decision about how we live.

We need that same realization when we decide whether to design streets to speed traffic or whether we design them to make neighborhoods more livable.

Charles Siegel

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